You can double the original ATK of this card once per turn. If you used this effect, destroy this card during the End Phase.
Rulings
Individual Card FAQs
If "Karate Man" is equipped with "Megamorph" and its ATK is being halved, if you then activate its effect, its ATK is 2000. If you activate its effect and then equip it with "Megamorph" while your Life Points are greater than your opponent's, its ATK is 500. If "Karate Man" is equipped with "Megamorph" and you activate its effect, or if you activate its effect and then equip it with "Megamorph" while your Life Points are less than your opponent's, its ATK is 2000.
Netrep Q&As
Q: Would “Messenger of Peace” effectively stop “Karate Man” from using his effect? A: “Karate Man's” effect is Spell Speed 1, and it can only be activated during one of your own Main Phases. Since “Karate Man's” ATK would be over 1500 before you declare the attack, you definitely cannot attack after using “Karate Man's” effect if “Messenger of Peace” is on the field. Similarly, as “Karate Man” is a Spell Speed 1 effect, it cannot be used during the opponent's turn at all. So, if a “Gemini Elf” (for example) attacks your “Karate Man,” you don't get to use the effect and “Karate Man” is destroyed from battle. Steve Okegawa, 01/07/2004
EARTH|
Level 3|[ Warrior / Effect ]
ATK 1000|
DEF 1000